Are you asking about private messages sent through the WikiTree system by clicking on the [send private message] link after the Profile Manager's name on a profile? Whenever somebody clicks that link on one of your profiles (whether it's another member or an outside observer), they can contact you about that profile without your email address being revealed. If you answer that message through your own email service, then your address is revealed to the sender. So actually it's a feature, very useful IMHO, that allows others who may have additional info to establish contact with you. If you don't want to correspond, you just don't respond, or if you think you're being spammed, you're asked to forward the email to info@wikitree.
If I have completely missed the boat on your question, please post here again.